For a chemical reaction A + B ⇌ C + D

($${\Delta _r}{H^\Theta }$$ = 80 kJ mol^$$-$$1) the entropy change $${\Delta _r}{S^\Theta }$$ depends on the temperature T (in K) as $${\Delta _r}{S^\Theta }$$ = 2T (J K^$$-$$1mol^$$-$$1).

Minimum temperature at which it will become spontaneous is ___________ K. (Integer)

An exothermic reaction X $$ \to $$ Y has an activation energy 30 kJ mol^$$-$$1. If energy change $$\Delta$$E during the reaction is $$-$$20 kJ, then the activation energy for the reverse reaction in kJ is ___________. (Integer answer)

Dichromate ion is treated with base, the oxidation number of Cr in the product formed is ___________.

Number of bridging CO ligands in [Mn₂(CO)₁₀] is __________.